Dial locking device for a mechanical computer



April 10, 1956 E. T. FORTINI DIAL LOCKING DEVICE FOR A MECHANICAL COMPUTER Filed Dec. 4, 1953 IN V EN TOR. EHEL W000 T FOE T/N/ f-iTTOE/VEYS United States Pate DIAL LOCKING DEVICE FOR A MECHANICAL COMPUTER Earlwood T. Fortini, Newton, Mass., assignor to the United States of America as represented by the Secretary of the Air Force Application December 4, 1953, Serial No. 396,359

2 Claims. (Cl. 188-83) This invention is directed to an improved dial locking device whereby the angular setting of the dial is not afiected by the locking action and whereby no distortion or undue strain is imposed on the dial by the locking action. The invention has as its object the provision of an improved construction of dial locking means which will be certain or definite in action and which will require a simple movement of a manipulative member to enable a locking element to take efiect without disturbing the chosen setting of the dial. According to the invention, the manipulative member will be movable between locking and unlocking positions and detent means will be provided for releasably retaining the manipulative member in either of its positions. The invention is featured, further, by the provision of a crown or cylinder cam means which will be turned by the manipulative member to control the action of the locking device. Another feature of the invention is the provision of a thin peripheral extension of the dial proper, to whichextension the locking action will be applied so as not to aflect the dial surface or interfere with the view of the dial graduations.

Another object of the invention is to provide an improved dial locking device wherein the clamping element has a floating portion to prevent the transmission of adverse motion elfects from the locking arm to the dial to disturb the setting thereof.

Other objects and advantages of the invention will be readily apparent to those versed in the art from the following description taken in conjunction with the accompanying drawings wherein:

Fig. 1 is a partial perspective view of the improved dial locking device which is the subject of this invention as applied to a dial.

Fig. 2 is a cross-sectional view of the clamping apparatus showing the details of the control mechanism and is taken substantially along the lines 22 in Fig. 1.

Fig. 3 is a cross-sectional view showing the clamping elements in unlocked position.

Fig. 4 is a cross-sectional view as in Fig. 3 showing the clamping elements in locked position.

Fig. 5 is a bottom view of the structure shown in Fig. 2 of the drawings.

The details of the novel dial lock can be readily seen with reference to the drawings. A practical embodiment of the invention shown in Fig. l of the drawings is shown in application to a dial 1 secured toa shaft 2 journalled in a bearing in the plate 3 for rotation relative thereto. The particular dial 1 which is calibrated as shown has a thin web portion 4 secured to the rim of the dial and extending outwardly from the periphery of the dial. In the particular application shown here, the dial is used in conjunction with a Vernier scale 5. While a particular type of dial 1 structure is shown it is only intended as an example and is not to be construed as limiting in nature. In the locking of the dial shown the invention applies the lock through the web 4. The structure of the invention apparatus consists of an adapter plate 6 adapted to be secured in any suitable fashion to housing structure adja-' cent the dial which is involved by means of boltsfor example. Since the manner of attachment of the adapter plate is not pertinent to the novel lock structure, no details thereof are shown. The adapter plate has a circular, bearing aperture 7 therethrough and a recess 8 in one surface thereof in which is located a resiliently biased detent 9 adjacent such aperture 7. The detent normally extends from the surface of the adapter plate. Mounted on the adapter plate is a control arm 10, comprising a manipulative member integrally associated with a flanged portion 11 circular in nature and having two recesses 11' in the bottom surface thereof in spaced relation. The bottom surface of the flange abuts the surface of the adapter plate and the recesses therein are adapted to receive the detent 9 for retention of the control arm in lock and unlock positions. Fixed to and depending from the control arm or manipulative member 10 is an internally threaded stud 12 which extends through the aperture 1 in the adapter plate. A crown or cylinder cam 13 with a reduced sleeve hub surrounds and is keyed to the stud 12 and held in secured relation thereto by a washer and a bolt 14 threaded into stud 12 and clamping the washer in position as shown in the drawings. The hub of the cam has a rotatable bearing fit in the bearing aperture 7 of the bracket plate 6. The shoulder between the cam cylinder proper and its hub serves, by thrust engagement with the under surface of plate 6, to prevent the cam and the connected parts 12 and 10 from rising. The cam 13 as shown in cross-section has a vertically variable cam under surface. Connected to the surface of the adapter plate on the cam side thereof is a bracket 15 spaced from the cam and extending from the plate in inclined fashion having arms in which is connected a pivot pin 16. On the pin 16 is pivoted a rockable clamping arm 17. The arm 17 has an extending lug portion 18 for cooperation with the cam surface of cam 13 while the arm on the opposite side of cam 13, as shown in Fig. 2, has a notch 19 therein. Spring members 20 are wrapped around the pivot pin 16, with one end anchored on bracket 15 and the other end hooked into the notch 19 in the arm 17, the spring means thereby biasing the lug portion of the arm against the cam surface. On the end of the arm 17 opposite the end formed with the cam-following lug 18 is pivoted a shoe 30 on a pivot pin 21 and caged between the surface of the arm and the shoe element is a ball bearing element 22. As can be seen the clamping assembly is connected to the dial housing structure S so that the shoe portion 31) is normally adjacent one face of the dial web 4. It is noted that the shoe may be adjacent either face of the web, depending on the desired arrangement. To the housing structure S adjacent the other face of the web is fixed an anvil member 23 which cooperates with the shoe or arm 17 to form the lock means. As shown in Fig. 3 of the drawings, the web in free position is spaced intermediate the clamping shoe and the anvil.

In the operation of the dial lock the actuating cam 13 is rotated to a lock position by the control arm 10, and is detained in this position by the engagement of the detent 9 in the appropriate recess in the flange 11; movement of the cam to lock position brings the shorter cam surface in line with the lug portion 18 of the arm 17 permitting the spring means 20 to bias the arm 17 about its pivot axis to cause the shoe portion 30 on the arm 17 to engage the dial web and lock it against the anvil 23 by clamping pressure. It is noted that the shoe portion 30 which cages the ball bearing member 22 is in effect a floating shoe which structure prevents the motion caused by rocking of the lever about its pivot, when clamping action is effected, or the motion due to slackness in the pivot from being transmitted to the web to disturb the dial setting.

a of the invention. This lever mechanism is of a unit type said cam follower, biasing means for the lever'urging' the lever in a direction to" maintain the cam follower against construction and, as can be readily seen, requires no unusual precisionin construction or mounting, making it readily adaptable to many'applications. To emphasize the benefits .of, the subject invention it is pointed out:

a. The angular setting of a dial is not afiected by the locking action nor is there any undue stress or strain resulting therefrom.

b. On unlocking'there is complete freedom of the dia from frictional .drag.

c. The lock may be operated by-a rotation of the control arm of less than 60 by proper cam design, and the lock and unlock positions are positively determined.

d. The locking action is certain in that it is not dependent on operator judgement other than that he shift the member 10 between locking and unlocking positions, both appropriately marked, as is understood.

Other modifications and applications of the invention will be readilyapparent to those versed in the art from the disclosure of the preferred practical embodiment of the invention herein such for-example as a modification for.

more positiveinterrelation of the anvil and the clamping arm support structure. Such is considered within the scope of the invention. a

I claim: 7 1. A dial locking mechanism comprising a thin web rigidly extending outwardly from the dial rim and concentrio with the rim, an anvil and confronting clamp shoe respectively at opposite faces of said web and when spaced apart freeing the rim and, thereby, the dial for rotative adjustment to achosen setting, a fixed frame, a lever pivoted to the frame for carrying the clamp shoe and provided with a cam follower at one side of the frame, a crown cam journaled in the frame and formed with a cam edge also located at said side of the frame forengaging the cam edge and to bring the clamp shoe into coaction with the anvil to'clamp said web between them and thereby to lock the dial in a chosen setting, and an operating member for the cam fixed thereto at the side of the frame opposite the' cam edge and'cam follower to rotatively adjust the cam between dial-unlocking. and locking positions in the former of which a high portion of the cam engages the follower to hold the clampshoe away from the anvii, against the influence of the biasing means and in the latter of which positions a low portion of the cam edge coacts with the follower to enable said biasing means to bring the clamp shoe into clamping coaction with the anvil for clamping said web and thereby locking the dial in its chosen setting.

2. A dial locking machanism as defined in claim 1, said frame having a bearing aperture and the crown cam having a reduced hub rotativelyfittinginto said aperture to journal the cam in the frame, with the shoulder between the hub and cam proper acting against one side of the frame and said operating member actingagainst the opposite side of the frame, whereby the cam is substantially fixed in axial position, and. detent means for irnpositively retainingthe cam in either' of its locking and unlocking positions.

References Cited in the file of this patent UNITED STATES PATENTS 7 France Oct. 13, 1909 v ML; 

